By default, Ironic deploys images to iSCSI shares exposed by IPA. We also support a different deploy method, when IPA fetches an image from a Swift temporary URL. Such approach should allow us scale better, especially in the undercloud, where 1. we have only one conductor, 2. we have Swift already, 3. we already use temporary URLs.
This may need configuring Swift temporary URLs and configuring Ironic to use them. Then we need to document both supported deploy method. Finally, we should consider switching to deploy_interface=direct by default, leaving "iscsi" as an option.